Malrotation with a Midgut Volvulus

·     Torsion of entire gut around superior mesenteric artery (SMA) due to a short mesenteric attachment of small intestine in malrotation

·     Age

o     Usually neonate or young infant

o     Occasionally older child and adult

·     Associated with (in 20%)

o    Duodenal atresia

o    Duodenal diaphragm

o    Duodenal stenosis

o    Annular pancreas

·     Pathophysiology:

o    Degree of twisting is variable and determines symptomatology

o    Severe volvulus (= twist of 3 1/2 turns)

§   Can result in bowel necrosis

·     Acute symptoms in newborn (medical emergency)

o   Bile-stained vomiting

§   Intermittent

§   Postprandial

§   Projectile

o   Abdominal distension

o   Shock

·    Intermittent obstructive symptoms in older child

o   Recurring attacks of nausea

o   Vomiting

o   Abdominal pain

o   Failure to thrive (hypoproteinemic gastroenteropathy as a result of lymphatic + venous obstruction)

·     Plain film findings

o       Dilated, air-filled duodenal bulb and paucity of gas distally

§   "Double bubble sign" = air-fluid levels in stomach and duodenum

o       Isolated collection of gas-containing bowel loops distal to obstructed duodenum = gas-filled volvulus = closed-loop obstruction

§   From nonresorption of intestinal gas secondary to obstruction of mesenteric veins

·     Barium studies

o   Duodenojejunal junction (ligament of Treitz) located lower than duodenal bulb and to the right of expected position

o   Spiral course of midgut loops = "apple-peel / twisted ribbon / corkscrew" appearance (in 81%)

"Corkscrew" duodenum in malrotation with a midgut volvulus

o       Duodenal-fold thickening and thumbprinting (mucosal edema + hemorrhage)

o       Abnormally high position of cecum

·        CT findings

·        Whirl-like pattern of small bowel loops and adjacent mesenteric fat converging to the point of torsion (during volvulus)

·        SMV to the left of SMA (NO volvulus)

·        Chylous mesenteric cyst (from interference with lymphatic drainage)

·        US findings

o       Clockwise whirlpool sign = color Doppler depiction of mesenteric vessels moving clockwise with caudal movement of transducer

o       Distended proximal duodenum with arrowhead-type compression over spine

o       Superior mesenteric vein to the left of SMA

o       Thick-walled bowel loops below duodenum and to the right of spine associated with peritoneal fluid

·        Angio fIndings

o       "Barber pole sign" = spiraling of SMA

o       Tapering / abrupt termination of mesenteric vessels

o       Marked vasoconstriction and prolonged contrast transit time

o       Absent venous opacification / dilated tortuous superior mesenteric vein

·        Complications

·        Intestinal ischemia and necrosis in distribution of SMA (bloody diarrhea, ileus, abdominal distension)

·        DDx:

·        Pyloric stenosis (same age group, no bilious vomiting)